Abstract
The goal of this study is to investigate groundwater contamination from sewage disposal lake in Enjela area. In the study, twenty nine wells are assigned in seven sectors surrounding the sewage disposal area. The wells cover around 77 square kilometres. During this study, field and laboratory measurements are conducted. The field measurements include determining the location of wells related to the lagoon and the water depth related to mean sea level. The laboratory measurements include chemical and biological analyses for samples collected from the wells and sewage lagoon. Chemical analyses include determination of pH, EC, TDS, K+ , Na+ , Ca2+, Mg2+ , NO3 ˉ , PO4 3- , HCO3ˉ, and Clˉ. The indicators of biological contamination included coliform bacteria, COD, and BOD. According to the conducted analyses and measurements, the following results can be summarized. The study area is distinguished by the natural groundwater movement in the northeast direction. Concerning the chemical pollution, most of the wells are contaminated by potassium especially in the vicinity of sewage lagoon. For biological contamination, the wells are highly contaminated except those are far from lagoon. Due to its location and according to Simpson ratio, the groundwater in the study area is affected by seawater intrusion. Finally, based on this study, some recommendations are listed that might minimize the effect of this pollution if they are implemented. Keywords: Groundwater, aquifer, sewage water, chemical contamination, biological contamination